In the commercial world, copper supplementation is very common in growing pigs as high levels will help to increase growth rates. In a smallholder situation, I would expect that most pig feeds would provide enough. Copper is a trace element in pigs so they actually require very little and deficiencies are quite rare. Copper toxicity can cause liver failure.

One thing to note is that sheep are very susceptible to copper toxicity so do not feed cattle or pig food to sheep!